A vial of the Exagon Serum is recommended to be applied once a week after hair has been washed and while still wet. Using the tips of fingers, the treatment should be gently massaged into the scalp in circular motions for a minimum of two minutes. Leave it. Don’t Rinse. In cases where hair-loss is more visible, two to three vials of the lotion can be applied for four weeks, and then once a week as normal for continual maintenance.